With the recent state-level legalization of the use of marijuana, several jurisdictions (e.g., Colorado, Washington) have passed regulations regarding the permissible levels of (−)-trans-Δ9-tetrahydrocannabinol ((6aR,10aR)-delta-9-tetrahydrocannabinol) (aka. delta-9-THC, delta-9, Δ9) in the blood. There are, however, no screening methods amenable to road-side law enforcement currently on the market which are specific for delta-9-THC.
Habitual users of marijuana can have high levels of tetrahydrocannabinol-based metabolites in their system, including delta-9-THC. Delta-9-THC is the active ingredient in marijuana capable of causing intoxication and therefore the target of interest for screening for intoxication. Delta-9-THC is rapidly converted in the body to other forms such as hydroxyl-THC and carboxy-THC. As the many forms of THC are lipophilic, the compounds are stored in fat cells and will gradually eliminate from the body over the course of several weeks. The short timeframe conversion of delta-9-THC compounds to metabolites, to the long timeframe elimination of the metabolites from the body of a habitual user, results in a small volume of delta-9-THC being present in the individual's body compared to the higher volume of metabolites being present. Current diagnostic screening tests (typically performed in urine for workplace drug testing) utilize reagents which seek to catch all forms of THC. In jurisdictions where marijuana is illegal this is an extremely convenient consequence, as significant levels of THC will be available for screening. However, in jurisdictions where marijuana is legal, any non delta-9-THC-based metabolites can interfere with accurate detection of levels of any delta-9-THC-based metabolites and compounds in an individual's bloodstream. In a habitual user's blood, the amount of metabolite can be thousands of times greater than an amount of delta-9 THC. The problem of detecting delta-9 THC is further exacerbated by the low levels of delta-9 THC in the bloodstream. Exemplary values for intoxication determination are in the states of Colorado, Montana, and Washington a person is considered intoxicated if the level of delta-9-THC in an individual's bloodstream is at, or exceeds, 5 nanograms/milliliter (ng/mL), and in Nevada, 2 ng/mL.